Calendering apparatus



April 3, 1962 M. D. STONE CALENDERING APPARATUS 2 Sheets-Sheet 1 FiledMarch 15, 1957 INVENTOR.

Pm mOEm HIS ATTORNEY M ORRIH D. 5 TONE n MU April 3, 1962 Filed March13, 1957 M. D. STONE CALENDERING APPARATUS 2 Sheets-Sheet 2 INVENTOR. M1mm D. S TONE BY ['[IS ATTORNEY This invention relates to calenderingapparatus as employed in the manufacturing of thin strip-likenon-metallic material such as rubber, plastic, paper, textiles and thelike. More particularly, the invention disclosed herein has to do withnovel means adapted to render the material engaging roll or rollsnon-deflective thereby to produce a calendered product characterized bya constant thickness throughout its width.

Although apparatus as presently employed in processing theaforementioned materials differs somewhat depending upon theconstruction characteristics and operational functions, the novelfeatures of the present invention, as will be apparent to those skilledin the art, can be just as Well realized in one of the types set forth.However, in the interest of brevity, it is felt only necessary todiscuss the present invention in detail as employed in conjunction witha paper calendering apparatus and in a lesser degree as applied to arubber calender.

In the manufacturing of various types of papers, the calenderingoperation plays a vital part in the perfection of the finished productboth as to its uniformity in thickness across its width and in thesurface properties, i.e., smoothness, luster or shine of the paperssurface. Whether it be a machine calender, breaker calender, smoothingcalender or supercalender, the lower supporting roll, or what iscommonly referred to as the king roll, is subject to the entire weightof the other rolls of the stack, plus the external pressures applied tothe assembly by means of screws or other means. The lower roll beingsupported normally only at its ends deflects under this weight to agreater or lesser extent depending upon its length so that the materialpassing between the rolls would have an objectionable pressure andthickness across its width. To obviate this undesirable condition theking roll and one or more other rolls of the stack are provided with acrown, i.e., the roll surfaces are shaped in such a fashion as toprovide a gradually increasing diameter from the ends to the center ofthe roll. in this manner the inherent deflection is compensated forwhereby a uniform pressure is obtained at the nip of the two cooperatingrolls. However, crowning of the rolls is effective only for theparticular calculated pressure and paper width for which it was designedand only under such conditions does it afford a uniform pressure at thenip of the cooperating rolls. Inasmuch as the calendering pressure mustbe adjustable and the nips frequently changed to meet the optimumoperation conditions for the many types and grades of paper which arenormally produced, this requires a different crowned roll or rolls foreach operation from which it is obvious that the convenience and economyof the operation are seriously jeopardized.

The present invention provides means in the form of a supporting rolladapted to engage with the bottom roll of a calender stack at two spacedpredetermined points across the length thereby limiting materially thedeflection of bottom roll and the rolls of the stack are thus providedwith true horizontal calendering surfaces at the nips to yield a sheethaving a constant thickness throughout its width. This supporting rollmay take the form of an arbor having lands located thereon at pointsequidistant from its ends and spaced from each other by a distance ofapproximately .55 of the desired width of the material to be calendered.There are various forms for applying the principle of a land roll tocontrol and limit the deflection tes atent ice of other rolls, such asin a rubber calender, where it may be feasible to provide several landedrolls in order to take advantage of the invention herein disclosed.Normally, when a roll is subjected to pressure and supported at itsends, the deflection curve is a continuous are extending from either endof the roll, with the greatest degree of defiection at the centerthereby tending to cause the greatest variation in cross-sectionalthickness at the center of the sheet, unless compensated for bycrowning. In a calender incorporating the features of the landsupporting roll, as herein disclosed, the roll which is to be renderednondeflective is free at its ends permitting the ends of the roll todeflect in a direction toward the supporting land roll and the portionof the roll intermediate the two points engaged by the lands also todeflect toward the supporting land roll. The net result of this actionis therefore to reduce very greatly the magnitude of the deflection ofthe calender roll which, for practical purposes, may be considered to benegligible.

Accordingly, the principal object of this invention is to provide anexternal supporting roll for one or more rolls of a calenderingapparatus having a body portion and a pair of enlarged diameter portionsspaced apart from one another and equidistant from the perpendicularaxis of the roll whereby the deflection of the calender rolls is greatlyreduced.

It is another object of this invention to provide a supporting orbacking up roll, having lands spaced along its length, for one or morerolls of a calendering apparatus of which the lands are spaced apartfrom one another a distance of the order of .55 of the width of thematerial being calendered.

It is a still further object of this invention to provide a roll havinglands composed of replaceable sleeves made of a material softer than thecalender rolls thereby to prevent marking of the calender roll surfaces.

It is another object of this invention to provide a roll having landswhich are adjustable axially so as to provide the most optimumcalendering conditions.

These objects, as well as the various other novel features andadvantages of this invention, will become apparent when the followingdetailed description is read in conjunction with the accompanyingdrawings of which:

FIG. 1 is a front elevational view of a paper calender incorporating thefeatures of the invention herein disclosed;

FIG. 2 is an end sectional view taken on lines II-ll of FIG. 1;

FIG. 3 is a front elevational view of a paper calender constructed inaccordance with the practice of the prior art;

FIG. 4 is a front elevational view of a rubber calender in which thefeatures of the present invention have been incorporated;

FIG. 5 is a sectional end view taken on lines V-V of FIG. 4;

FIG. 6 is a sectional view of a modified form of the supporting rollshown in FIGS. 1 and 4, and

FIG. 7 is a view showing the lower rolls of the calender illustrated inFIG. 1 with which there is employed another modified form of supportingroll.

With reference to FIGS. 1 and 2 in which the present invention is shownto be incorporated in a paper calender, the calender comprisesessentially spaced vertically disposed frames 11 which at their basesare secured to suitable foundations and at their tops connected togetherby means of separator beams 12 thereby to provide a very rigidstructure. Each frame is provided with a vertically extending windowinto which there is received a stack of rolls consisting of a top roll13, a series of intermediate smaller diameter rolls 14, a bottom roll 15of the same diameter as roll 13 and directly below this bottom roll asupporting roll 16. The roll ends in the case of the rolls 13, 14 and 15are freely mounted in the frames being provided with babbitt or rollerbearings each having individual chock or bearing housings which serve toguide the rolls vertically in the windows so that by reason of theconstruction very little pressure is actually imposed upon theirbearings. The bearings for the supporting roll 16 being subject to theentire weight of the stack are usually of the water-cooled babbitt orroller type, but they may also be of the anti-friction type. Althoughnot shown, pressure applying means may be provided at the top of thecalender which may be of the pneumatic, hydraulic or mechanical typewhereby addiional but controlled pressure may be applied to the top roll13 and transferred thereby through the intermediate 5211s 14 to thebottom roll 15 and land supporting roll The enlarged diameter or landportions 17 of the supporting roll 16 are symmetrically located withrespect to the center line of the calender and for best results thedistance between the lands should be of the order of .55 of the width ofthe paper to be calendered. In the particular form shown, the supportingroll 16 is positively driven and the remainder of the rolls of the stackrotated by friction but alternately the bottom roll 15 might be driven.A conventional calender is illustrated in FIG. 3 and it consists of apair of frames 11a secured at their bases to a suitable foundation andconnected together at their upper portions by suitable separator beams12a. Each frame is provided with vertical openings or windows withinwhich the ends of top roll 13a, intermediate rolls 14a and king roll 15aare slidably mounted in suitable bearing supports. Although not shown inthe drawing, adequate pressure applying means normally mounted at thetop of the calender may be employed for impressing upon the roils thecontrolled pressure required for carrymg out a particular calenderingoperation. I To better understand the remarkable effect that the landsexercise in maintaining the bottom roll 15 straight and undeflected,reference is made to the diagrammatic illustrations shown in FIG. 1 ofthe improved calender and FIG. 3 of a calender constructed in accordancewith the prior art. By comparing the relative deflections of the bottomroll 15 of the improved calender with the kmg roll 15a of theconventional calender, the advantages gained by employing a supportingor backing roll with lands are apparent to one skilled in the art. It isof interest to note that in the improved calender the bottom roll 15 isof a greatly reduced diameter as compared with "a e king roll 15a of theconventional calender of FIG. 3, the reduction being made possible bythe employment of the additional supporting roll 16. The king roll 15aof the conventional calender is usually crowned so that underpredetermined rolling conditions the roll, although deflected during thecalender operation, will maintain the nip in substantially a truehorizontal plane. However, as mentioned heretofore, by reason of thevarying conditions under which the calender will be required to perform,the crown given to the king roll 15' will not properly compensate forthe roll deflection under any conditions other than normal. Thus, it isapparent that the paper being processed will have characteristicobjectionable variations in its transverse cross-sectional thickness.

in the improved calender shown in FIGS. 1 and 2, it is not necessary toemploy crowned rolls inasmuch as the deflection of the bottom roll 15 isso reduced that for all practical purposes it may be considered to benegligible. This is attained by reason of the novel arrangement and thecharacter of the supporting roll 16 as disclosed in the presentinvention. Although as shown in FIG. 1, the supporting roll 16 willdeflect between points fixed by its bearings, the deflection of the rollaxis will not particularly aifect the bottom roll 15. The lands 17 arelocated approximately midway between the center and ends of the kingroll 15, preferably being spaced from each other by a distance of .55 ofthe width of the paper being calendered. As clearly shown in FIG. 1, theresistant pressure provided by the presence of the supporting roll 16 atits points of contact with the roll 15, instead of the axis of the roll15 deflecting in a continuous arc, as in the case of the conventionalcalender shown in FIG. 3, the axis will be displaced somewhat as shownby the deflection curve in FIG. 1. It is noted that since the outer endsof the roll 15 are not fixed, the deflection thereof will be in adirection toward the supporting roll 16 as will be the portion of theroll 15 intermediate the two points engaged by the lands. The net resultof this action is therefore to reduce greatly the magnitude of thedeflection of the king roll to such an extent that for all practicalpurposes it may be considered to be negligible and the nips of the stockwill be characterized by essentially parallel cooperating surfaces sothat the paper being calendered will issue from the last nip possessinga uniform thickness throughout its width. Considering the deflection atthe center of the roll with respect to the edge of the paper as A, ithas been determined that the maximum deflection of the bottom roll 15within the width of the paper of the calender disclosed, 8, herein willbe of the order of .005 A, for the same roll diameter.

In FIGS. 4 and 5 a rubber calender has been arbitrarily selected forillustrating the features of the present invention in connection with acalender other than of the type for processing paper. The form shown isa three-roll type calender including vertical housings 2t rotatablysupporting a fixed center roll 21 and vertically disposed outer rolls 22and 23 adapted to engage the opposite sides of the roll 21' which areadjustable in the usual fashion relative to the roll 21. The rolls in aconventional calener are normally supported at their ends so that theyare permitted to deflect between their bearings thereby causing therubber sheet delivered by the calender to have a non-uniform thicknessacross its width. To obviate this condition, the outer rolls 22 and 23are each supported by land rolls 24 and 25 constructed in a similarfashion to the roll proposed for the paper calender and arranged on thesame vertical centerline as the rolls 22 and 23. External pressure issupplied by suitable means, not shown in detail, to the two ends of thetwo supporting rolls 24 and 25. As in the case of the paper calender,the arrangement of the lands centrally with respect to the centerline ofthe calender and spaced apart by a distance of the order of .55 of thewidth of the material to be processed will restrict the deflection ofthe rolls 22 and 23 so effectively that for all practical purposes itmay be considered to be negligible, thereby causing a product to beyielded having a uniform thickness throughout its width.

In FIG. 6 a modified form of the land roll is illustrated in which aroll is provided having a metallic center body portion 18 and two landportions 19 made up in the form of sleeves of paper, rubber, micarta orthe like, which materiais are capable of carrying the pressures involvedbut are of such softness compared with the main body of the roll 15 thatno marking of the roll 15 can take place. The sleeves are replaceable sothat afte they have become worn, the rolls are removed from service andthe sleeves slipped off and new ones substituted therefor. Normally, theroll having the lands made out of the same material as the main bodythereof will be satisfactory. However, when extremely large pressuresare to be encountered the use of the modified form as shown in FIG. 6may be more desirable.

It may be desirable in connection with a calender adapted to processmaterial covering a wide range of widths to provide for adjustment ofthe land portions axially either towards or away from one another. InFIG. 7 a supporting roll incorporating these features isdiagrammatically illustrated. By axially adjusting the lands, thedistance between them may be maintained substantially of the order of.55 of the width of the material being processed. In this construction anon-rotatable shaft 26 is provided and adapted to carry two adjustablelands 27 which are rotatably supported by means of spherical rollerbearings 28 mounted on the shaft. The inner races of the bearings extendoutwardly and are provided with suitable set screws 29 adapted to bedrawn up tight against the shaft 26. Not only does this arrangementprovide for ready adjustment of the lands but it also permits the outerraces of the bearings to move angularly on deflection of the shaft andrelative to their inner races whereby full rolling contact will bemaintained between the lands and the bottom roll.

In accordance with the provisions of the patent statutes, I haveexplained the principle and operation of my invention and haveillustrated and described what I consider to represent the bestembodiment thereof. However, I desire to have it understood that withinthe scope of the appended claims, the invention may be practicedotherwise than as specifically illustrated and described.

-I claim:

1. In a calender for processing material having a substantially uniformthickness across its width comprising at least one pair of materialengaging rolls between which the material to be calendered is passed, asupporting roll for at least one of said material engaging rolls, a pairof lands on said supporting roll in contact with said material engagingroll at points spaced apart from one another by a distance less than thewidth of the strip to be reduced, the spacing of said points bearing adirect relationship to the width of material being processed and of theorder of .55 thereof, thereby to control and limit the extent to whichsaid material engaging roll is deflected during the calenderingoperation, said lands being made of a material softer than saidsupported material-engaging roll thereby to prevent marking of saidroll.

2. In a calender for processing material having a substantially uniformthickness across its width comprising at least one pair of materialengaging rolls between which the material to be calendered is passed, asupporting roll for at least one of said material engaging rolls, a pairof lands on said supporting roll in contact with said material engagingroll at points spaced apart from one another by a distance less than thewidth of the strip to be reduced, the spacing of said points bearing adirect relationship to the width of material being processed and of theorder of .55 thereof, thereby to control and limit the extent to whichsaid material engaging roll is deflected during the calenderingoperation, said lands consisting of spherical anti-friction bearingsadapted to rotate relative to said supporting roll.

References Cited in the file of this patent UNITED STATES PATENTS165,754 Richardson July 20, 1875 864,660 Love Aug. 27, 1907 1,614,424Coe Jan. 11, 1927 1,785,986 Speer et a1 Dec. 23, 1930 1,912,709 KaneJune 6, 1933 1,953,165 George Apr. 3, 1934 1,953,190 Paterson Apr. 3,1934 1,994,662 Paterson Mar. 19, 1935 2,356,842 Helmond Aug. 29, 19442,537,653 Critchfield et a1 Jan. 9, 1951 2,648,122 Hornbostel Aug. 11,1953 2,651,103 Hornbostel Sept. 8, 1953 2,651,241 Hornbostel Sept. 8,1953 2,777,330 Barclay Jan. 15, 1957 2,907,235 Murakami Oct. 6, 1959FOREIGN PATENTS 436,111 Germany Oct. 23, 1926

